Date: Mon, 31 Jan 2005 13:31:34 -0800 (PST)
From: Stephan Szabo <sszabo@megazone.bigpanda.com>
To: Don Drake <dondrake@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: plpgsql functions and NULLs
In-Reply-To: <6c21003b0501301141234c256b@mail.gmail.com>
Message-ID: <20050131132701.G12960@megazone.bigpanda.com>
References: <6c21003b0501301141234c256b@mail.gmail.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


On Sun, 30 Jan 2005, Don Drake wrote:

> OK, I have a function that finds records that changed in a set of
> tables and attempts to insert them into a data warehouse.
>
> There's a large outer loop of candidate rows and I inspect them to see
> if the values really changed before inserting.
>
> My problem is that when I look to see if the row exists in the
> warehouse already, based on some IDs, it fails when an ID is NULL.
> The ID is nullable, so that's not a problem.
>
> But I'm forced to write an IF statement looking for the potential NULL
> and write 2 queries:
>
> IF omcr_id is null
>    select * from ....
>    WHERE omcr_id is NULL
>    AND ...
> ELSE
>    select * from ....
>    WHERE omcr_id=candidate.omcr_id
>    AND ....
> END IF;

Hmm, perhaps some form like:

WHERE not(candidate.omcr_id is distinct from omcr_id)